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C02/include/strptn.a02
2018-01-28 13:30:49 -05:00

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;Wildcard String Match Function for C02
;C02 Wrapper for Pattern Matcher Routine
;Args: X,Y = Pointer to Pattern String
;Requires: DSTLO,DSTHI = pointer to null-terminated String
;Calls: SETSRC, PTTRN
;Returns: A=$FF if match
;Match passed string against pattern pointed to by src
STRPTN: JSR SETSRC ;Initialize source string variables
JSR PTTRN ;Do pattern match
BMI STRPTM ;If string length exceeded
BCS STRPTX ;or no match found
STRPTM: INX ; Change X from $FF to $00
STRPTX: TXA ;Set Result to TRUE or FALSE
RTS ;and Return
;Pattern Matcher by Paul Guertin, 30 August 2000
;from http://6502.org/source/strings/patmatch.htm
;
;Modifications by Curtis F Kaylor, 23 May 2017
;changed labels to conform to c02 library standards
;moved index storage to memory to allow indirect reference to pattern
;added exit with N=1 if strings exceed 128 characters
;
;Requires: SRCLO,SRCHI = pointer to null-terminated Pattern
; DSTLO,DSTHI = pointer to null-terminated String
;Sets: X - $FF
; TEMP0 - index into pattern
; TEMP1 - index into string
;Uses: 4 bytes of stack for each '*' in pattern
;Affects: A,Y,Z
;Returns: C - 1 if String matches Pattern, otherwise 0
; N - 1 if String or Pattern longer than 127 characters, otherwise 0
PTTRNQ EQU "?" ;Question mark Matches exactly 1 character
PTTRNA EQU "*" ;Matches any number of characters (including 0)
PTTRN: LDX #$00 ;Initialize pattern pointer to 0
STX TEMP0
DEX ;Initialize string pointer to 255
STX TEMP1
PTTRNL: LDY TEMP0
LDA (SRCLO),Y ;Get next pattern character
CMP #PTTRNA ;If it's a '*'
BEQ PTTRNS ; Jump to star match
INC TEMP1 ;Else point to next string character
LDY TEMP1
CMP #PTTRNQ ;If it's a '?'
BNE PTTRNR ; Replace with string character
LDA (DSTLO),Y ; If End of String
BEQ PTTRNX ; Exit with no match found
PTTRNR: CMP (DSTLO),Y ;If pattern character <> string character
BNE PTTRNX ; Exit with no match found
INC TEMP0 ;Else point to next pattern character
BMI PTTRNX ;If max length exceeded, exit no match
CMP #0 ;If not string terminator
BNE PTTRNL ; Check loop
PTTRNF: RTS ;Else exit with match found
PTTRNS: INC TEMP0 ;Skip '*' in pattern
LDY TEMP0
CMP (SRCLO),Y ;If next pattern character is '*'
BEQ PTTRNS ; loop back to skip
PTTRNT: LDA TEMP0 ;Push pointer into pattern
PHA ; onto stack
LDA TEMP1 ;Push pointer into string
PHA ; onto stack
JSR PTTRNL ;Recursive call to match rest of string
PLA ;Pop pointer into string
STA TEMP1 ; off of stack
PLA ;Pop pointer into pattern
STA TEMP0 ; off of stack
BCS PTTRNF ;If rest of string matched, exit with match
INC TEMP1 ;Skip next string character
BMI PTTRNX ;If max length not exceeded
LDY TEMP1
LDA (DSTLO),Y ;and not string terminator terminator
BNE PTTRNT ; loop to pattern check
PTTRNX: CLC ;Clear carry
RTS ; and return